If you had a car equipped with adaptive cruise control and a lane-tending system, you could drive 100 miles of interstate—blindfolded.

Former C/D senior editor Phil Berg has drawn me into numerous mobile capers, among them a nonstop cross-country drive in a VW Jetta diesel with a monster fuel tank and a PVC funnel that served as a direct-deposit urinal. Toward the end of that odoriferous trek, we’d become the Wood Brothers of on-the-fly driver changes, making the swap in about 15 seconds.

Having thus grown accustomed to “no one actually safely operating the vehicle,” as Berg put it, he suggested that some of the technology that makes autonomous cars autonomous has already been attached to vehicles available to you and me. “It wouldn’t surprise me,” he unfortunately uttered aloud, “that if you had a car equipped with adaptive cruise control and a lane-tending system, you could drive 100 miles of interstate—blindfolded.”

ATTEMPT NO. 1: Berg and I lit out in C/D’s long-term 2011 Infiniti M56S, equipped with the $3000 Technology package, including intelligent cruise control, blind-spot warning/intervention, and lane-departure warning/intervention. In this case, “warning” was exactly that—flashing orange lights and a chime—whereas “intervention” meant that events were actively controlled. Specifically, the brakes would be automatically applied gingerly to an inside wheel, thus turning the car a few degrees away from the highway’s edge or center markers and back to straight-ahead. What could go wrong?

I wore a pilot’s IFR flight hood so that my view was confined to the dash and to my own groinal region. Alas, I was safely able to control the Infiniti for, oh, maybe 300 feet before Berg shouted something about an abandoned Honda, then wrested the wheel from my mitts.

As the Infiniti drifted over the lane markers, there were helpful klaxons, sure, and the brakes would pulse two or three times. But the braking shepherded the car back to straight-ahead in only half of its attempts. If the car approached the lane markers at a very shallow angle on a highway with little or no crown and no disruptive potholes, well, it would usually make a useful correction. But if a whole slew of other driving conditions weren’t in cosmic alignment, the car would carve through the centerlines, brakes and chimes be damned. The system wasn’t sufficiently aggressive. Wearing the IFR hood, I’d have failed to drive far anyway because I needed warning lights to show me “too far left” or “too far right” in order to countersteer correctly.

ATTEMPT NO. 2: Next we summoned a $157,985 CL63 AMG from Mercedes-Benz. It sported the sort of electronics you’d expect on a commercial Boeing product, including the $2950 Driver Assistance package (crash prevention, adaptive cruise control, active lane-keep assist, and, for all we know, a flight simulator and a popcorn maker).

On the interstate, the Benz’s gadgetry proved semi-effective at recognizing solid edge lines—especially those that were yellow—but was iffy at identifying the intermittent center stripes, and even then the stripes had to be bright white, no smudges, dry-cleaned only. When edge lines were encroached, the steering would vibrate in a series of three pulses over 1.5 seconds, although the pulsing was so subtle that we sometimes mistook it for road imperfections or the onset of delirium tremens. If the lane-marker encroachment then continued, the brakes were automatically applied to turn the car—much more aggressively than the Infiniti’s—and it could often pull itself back to midlane, hunky-dory. Just as important, an icon on the speedo showed which direction—left or right—the car had most recently drifted, allowing me to make manual corrective guesstimates. And so I should have driven the Benz to Chicago while looking at my crotch. In reality, I managed only a quarter-mile because the lane-tending camera was too insistent about wanting perfect stripes. Overall, it was correctly reacting to solid side markers in about one out of three encroachments and was reacting to the intermittent centerlines in maybe one out of ten. Strike two.

ATTEMPT NO. 3: Berg began frequenting a local Lexus dealer, offering C/D T-shirts, magazines, and a fabricated story that doesn’t bear repeating. In that manner, he scooped up a dandy little HS250h with lane-keep assist, and again we set off to annoy long-distance truckers.

When the Lexus encroached side-marker lines, there were warning beeps aplenty. In fact, it sounded like a microwave oven. Moreover, the steering was quite authoritative about pulling the car back in line—the electric steering itself would make the correction, rather than the brakes. But the system was “seeing” only 70 percent or so of the markers, and after a session of ping-ponging between side- and centerlines, the Lexus would inevitably encroach at an angle so steep that a lot more than gentle steering was required to prevent a nonapproved FAA flight into the ditch. What’s more, the lane-keep icon on the dash didn’t inform whether we’d wandered left or right. I’m pretty sure that numerous citizens in my wake called to report a 58-year-old drunk wearing a plastic party hat in a car he can’t afford.

“You failed,” Berg said, as if this had been my idea. Still, we learned that the hardware necessary to drive autonomously on an interstate already exists and is available to all. But that hardware, and in particular the software that controls it, remains soft.